Improvement in burglar-alarms



UNITED STATES PATENT OEEIoE.

THOMAS POWELL, OF PHILADELPHIA, PENNSYLVANIA.

IMPROVEMENT IN BURGLAR-ALARMS.

Specification forming part of Letters Patent No. 163,524, dated May 18, 1875; application filed April 17, 1875.

To all whom it may concern Be it known that I, THOMAS POWELL, of Philadelphia, Pennsylvania, have invented an Improved Burglar-Alarm, of which the following is a specification:

The object of my invention is to construct a simple, cheap, and effective device for attachment to a door, and for causing an alarm when the door is opened by thieves or burglars; and this object I attain in the manner which I will now proceed to describe, reference being had to the accompanying drawing, in which Figure 1 is a front view of the burglaralarm, and Fig. 2 a plan view.

To the door A is secured a metal frame, B, and to the latter are secured the works of an ordinary cheap clock, the plate D, in conjunction with a rear plate, serving to carry these works, which are of the usual character, but in a position the reverse of those of an ordinary clock, and which-are too well known to need minute description or illustration. There are the usual train of wheels, the coiled spring for setting the wheels in motion, and the escapement, the arm G, to which the pendulum is usually connected, projecting upward, and during its vibrations, when released, striking a bell or other sonorous object, which is secured in a suitable position to the frame B. Across the frame B, and guided by the same, extends a sliding bar, H, the movement of which is restricted by a projection, a, on the plate, adapted to a slot in the bar, the tendency of which, owing to the action of the spring I, is to move in the direction of the arrow. The bar is connected to the lower arm of a lever, K, the upper forked arm of which is adapted to a-pin on the lower arm of the lever M, the upper arm of the latter bearing against the escapement-arm G, and preventing its vibration when the bar H is in the position shown in Fig. 1. To the end of the bar is hinged a catch, H, which can be hooked onto a pin, m, projecting from the frame of the door, on opening which the catch will be released from the pin, and the sliding bar will be moved by the spring I in the direction of the arrow, thereby causing the upper arm of the lever M to recede from the escapementarm G, and permitting the latter to be vibrated freely by the action of the coiled spring and escapement.

The movement of the escapement-arm may be arrested by a pin, a, arranged to slide in the frame, the pin being'moved outward when the device has to be set for operating as a burglar-alarm, and inward, so as to restrain the escapement-arm, when the use of the device has to be discontinued.

It will be evident that the alarm may be attached to a window or window-shutter.

I claim as my invention- A burglar-alarm in which are combined the spring sliding bar H and its catch, the levers K and M, and the escapement-arm G of clockwork mechanism.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

THOMAS POWELL.

Witnesses HUBERT HowsoN, HARRY SMITH. 

